Various forms of communication systems have become nearly ubiquitous in modern life. For example, wired communication systems of various forms have been used for voice and data communication for quite some time. Various forms of digital subscriber lines (DSL) have been used for internet service provision (data communication) over wires originally installed for telephone voice service. Wired communication systems originally used for analog cable television service have also been adapted for digital cable and internet service provision. Wireless communication systems are commonly implemented with respect to telephones (e.g., cellular telephones, wireless telephone handsets, personal communication systems, etc.), personal digital assistants (PDAs) (e.g., mobile electronic mail platforms, mobile calendar systems, etc.), computers (e.g., wireless local area network (WLAN) enabled computers, cellular network enabled computers, etc.), and even appliances and peripherals (e.g., digital video recorders (DVRs), printers, digital photo frames, current weather display devices, etc.).
In order to provide for robust, often broadband, communication links, such systems have implemented multiple input and/or multiple output techniques. For example, in wireless systems spatial diversity techniques, wherein antennas at the transmitter and/or receiver are physically separated by some distance, have been used to mitigate effects of multipath and fast fading environments. Multiple-input and multiple-output (MIMO) techniques, wherein multiple antennas at both a transmitter and corresponding receiver are used, have been used to provide increased data throughput through spatial multiplexing techniques. Multiple antennas have also been used to jointly and optimally combat fading, and suppress self-interference due to multipath, multiple data streams, and/or interference from other sources. In wired systems, MIMO techniques have been used to effectively mitigate the effect of crosstalk.
Systems implementing multiple input techniques often utilize parallel input signal processing paths, whereby different signals are received at the multiple inputs and processed for combining by respective, parallel signal paths. The processing across these parallel signal paths may be done in parallel, serially, or a combination thereof. Directing attention to FIG. 1, a high level block diagram of a portion of a prior art communication system implementing such parallel input signal processing paths in a master/slave configuration is shown as receiver 100. Specifically, receiver 100 includes received signal inputs 111 and 121, such as may be provided in a spatial diversity configuration, a MIMO configuration, etc., providing signal input to respective ones of input circuits 112 and 122. Input circuits 112 and 122 may comprise radio frequency (RF) tuner circuitry, such as mixers, filters, and/or other circuitry operable to provide selection of a desired frequency band or channel(s). Input circuits 112 and 122 may also include analog to digital converters (ADCs) and/or other circuitry useful with respect to providing received signal processing. The signals of interest as provided by input circuits 112 and 122 are provided to a corresponding one of demodulators 113 and 123 for signal demodulation. Demodulators 113 and 123 operate to provide extraction of symbols or bits from a respective one of the signals of interest as well as to provide other processing (e.g., determining channel state information (CSI) of the associated communication channel).
In implementing a multiple received signal technique, receiver 100 of FIG. 1 provides for the combining of information derived from a signal received at one input with information derived from a signal received at another input. In order to do so, the parallel input signal processing paths must transfer certain intra system communication information. In the illustrated example, demodulator 123 operating as a slave demodulator provides, via link 101, information derived from signals received at received signal input 121 to demodulator 113 operating as a master demodulator for combining with information derived from signals received at received signal input 111. Such combining may comprise diversity combining using well known maximum ratio combining (MRC) or any type of processing used in spatial multiplexing or space-time coding, for example.
Combining techniques implemented in the art, such as the aforementioned MRC, typically utilize some form of CSI, such as signal to interference-plus-noise ratio (SINR), which is derived from the received signal, in order to combine received symbols (here which are also derived from the respective received signal inputs). Accordingly, operation of receiver 100 of FIG. 1 typically requires CSI associated with both received signal inputs 111 and 121 for combining symbol information derived from their respective received input signals. In the master/slave configuration of FIG. 1, demodulator 113, operating as the master demodulator, requires CSI from demodulator 123, operating as the slave demodulator, in addition to the symbol information derived from the signal received by demodulator 123. That is, both its symbol information and associated CSI are passed from demodulator 123 via link 101 to demodulator 113 in operation of receiver 100. Thus, intra communication system information comprises the symbol information and associated CSI.
The transfer rate of information between demodulators 113 and 123 may be appreciable, thus requiring that link 101 provide a relatively high speed link and/or a plurality of parallel paths. For example, where the signals of interest comprise the multicarrier mode of China Terrestrial Television Broadcast (CTTB), as known as Digital Terrestrial Multimedia Broadcast (DTMB) signals, the total transfer rate between demodulators may be approximately 156 Mbps (i.e., 72 Mbps (symbol information)+84 Mbps (CSI)=156 Mbps).
Such intra communication system information transfer requirements can be problematic to implement. For example, where demodulators 113 and 123 comprise separate integrated circuits or “chips,” the foregoing intra communication system information transfer may require a substantial number of integrated circuit package pins (e.g., on the order of 6 pins for each slaved input). Regardless of whether demodulators 113 and 123 comprise separate integrated circuits, the foregoing intra communication system information transfer rate may present an operational bottleneck, require appreciable circuit area to implement, consume considerable power, increase the cost of goods, etc.